1. Field of the Invention:
This invention relates to a draft apparatus for use with a spinning machine, especially for use with a pneumatic high speed spinning frame.
2. Prior Art
In a pneumatic spinning frame, a roving step is omitted so that a sliver is directly drafted on a draft apparatus including a plurality of pairs of rollers. Accordingly, thickness, configuration and the like of a sliver supplied to the draft apparatus have a serious influence on the quality of a yarn obtained therefrom which is later spun on the spinning frame. Further, since a sliver is an aggregate of a large number of fibers, even slivers which include a same number of fibers of the same thickness may be apparently different in thickness depending upon a degree of compression thereof. It is known that generally as the apparent thickness of a sliver becomes thinner, or in other words, as the degree of compression becomes higher to some degree, a spinning yarn obtained from the sliver becomes better in spinnability and thus in quality. To this end, it has been proposed that a guide having a sliver path therein which narrows in a direction of advancement of a sliver is disposed backwardly of a draft apparatus so that a sliver may be passed through and compressed by the sliver path in order to reduce the apparent thickness of the sliver before it is supplied to the draft apparatus. However, this arrangement cannot successfully decrease an expanding tendency of a bundle of fibers of the sliver. Besides, such a problem also arises that the parallellism of fibers of a sliver is disturbed by frictional contact of the sliver with the sliver path, thus resulting in deterioration of the quality of a yarn obtained.